This standard describes a method for the gravimetric determination of the combined content of at least 0.2% (w/w) niobium and tantalum and is applicable to the chemical examination of alloyed and high-alloyed steel. In the presence of tungsten, the annealed residue to be weighed contains tungsten oxide; if the sample contains more than 0.05% {w/w) tungsten, the deviations become too large. Of the phosphorus present, approximately 1/6 part ends up in the precipitate as phosphate; this interference is negligible in most cases. If the sample contains more than 0.5% (w/w) molybdenum or 0.1% (w/w) titanium, the residue to be weighed may contain small amounts of the oxides of these elements, causing the results to be a few hundredths of a percent off. can reach high. If necessary, correct the results for the presence of these elements according to section 6.4.
NEN 6213-1978 history
1978NEN 6213-1978 Chemical analysis of iron and steel - Gravimetric determination of the total content of niobium and tantalum in steel